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1, 0, 1, 2, 3, 4, 5, 4, 3, 2, 1, 2, 3, 4, 3, 4, 5, 6, 5, 6, 5, 4, 5, 6, 5, 4, 3, 2, 3, 2, 1, 2, 3, 2, 3, 4, 5, 6, 7, 6, 7, 6, 7, 8, 7, 6, 5, 6, 7, 6, 7, 8, 9, 10, 9, 10, 9, 8, 7, 8, 9, 8, 9, 8, 7, 6, 7, 8, 9, 8, 9, 10, 11, 10, 9, 10, 11, 10, 9, 8, 9, 10, 11, 10, 11, 10, 11, 12, 13, 14
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,4
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COMMENTS
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LINKS
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MAPLE
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A086144 := proc(n) option remember; if n=1 then 1 else
if combinat[numbpart](n) mod 2 = 1 then 1 else -1 fi;
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MATHEMATICA
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a071640[n_] := Sum[Mod[PartitionsP[i], 2], {i, 1, n}];
a[n_] := 2 a071640[n] - n;
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PROG
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(PARI) a(n) = my(x='x+O('x^(n+1)), p = 1/eta(x)); sum(i=1, n, (1-(-1)^(polcoeff(p, i)))) - n; \\ Michel Marcus, Jun 11 2019
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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Erroneous data for n>55 replaced, keyword sign added by Peter Luschny, Oct 05 2011
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STATUS
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approved
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